I've been plagued with this error code ever since I got my TDI-swapped Audi A4 back on the road. I'm pretty sure it's the reason why my cruise control isn't working.
Car is a 2001 Audi A4 Avant quattro that used to have an AWM 1.8T and manual trans. It now runs the engine, ECU and wiring harness from a 2005 Passat (BHW 2.0 PD TDI) mated to an 01E FTL 6-speed transmission. The TDI ECU is EDC16. There was a bit of wiring work needed to get the ECU to match up with the car's wiring, but it all went well and the car runs fantastic. The cruise control and this error code are the only thing left to resolve.
When looking at the wiring diagrams for each car:
- the VSS signal on the Passat goes to the transmission control module, which then gets sent to the instrument cluster and ECU (presumably via CAN bus).
- the VSS signal on the A4 goes to the instrument cluster, which then gets amplified and sent to the ECU via a white/blue wire straight to a specific pin.
I have it setup the A4 way, and it seems to work. It required adding a wire to an unused pin on the ECU. The speedometer is accurate and responds appropriately. However the reported speed in the ECU is always about 15% higher than the speedometer. I think this is where the error code comes from, and why the cruise control won't work.
I did a LOT of research, and I can't figure out why this is happening. Lots of people have swapped an 01E transmission into the B5.5 TDI Passat (albeit a FWD one, not quattro), and they can get cruise control working fine. This is actually how I learned which pin to send the VSS signal to on the ECU, other people figured it out before me.
As far as I know, the VSS ring works the same way on both cars. It has 8 magnetic poles that trigger a pulsed voltage on the VSS sensor, unless I'm wrong and the OEM Passat TDI automatic trans has 6 poles somehow... but then all those other 01E-swapped Passats would have had the same issue I'm having. So why is the ECU taking the signal that the instrument cluster is sending to it, and inflating the result by 15%?
For the record, the ECU is coded for a manual transmission and the tune has all the right gear and final drive ratios entered. And since it was for a B5.5 Passat, tire size is identical between the two cars. I'm not the first person to mate this engine to an 01E, although I may be the first to do it on a B5.5 A4 quattro.
Car is a 2001 Audi A4 Avant quattro that used to have an AWM 1.8T and manual trans. It now runs the engine, ECU and wiring harness from a 2005 Passat (BHW 2.0 PD TDI) mated to an 01E FTL 6-speed transmission. The TDI ECU is EDC16. There was a bit of wiring work needed to get the ECU to match up with the car's wiring, but it all went well and the car runs fantastic. The cruise control and this error code are the only thing left to resolve.
When looking at the wiring diagrams for each car:
- the VSS signal on the Passat goes to the transmission control module, which then gets sent to the instrument cluster and ECU (presumably via CAN bus).
- the VSS signal on the A4 goes to the instrument cluster, which then gets amplified and sent to the ECU via a white/blue wire straight to a specific pin.
I have it setup the A4 way, and it seems to work. It required adding a wire to an unused pin on the ECU. The speedometer is accurate and responds appropriately. However the reported speed in the ECU is always about 15% higher than the speedometer. I think this is where the error code comes from, and why the cruise control won't work.
I did a LOT of research, and I can't figure out why this is happening. Lots of people have swapped an 01E transmission into the B5.5 TDI Passat (albeit a FWD one, not quattro), and they can get cruise control working fine. This is actually how I learned which pin to send the VSS signal to on the ECU, other people figured it out before me.
As far as I know, the VSS ring works the same way on both cars. It has 8 magnetic poles that trigger a pulsed voltage on the VSS sensor, unless I'm wrong and the OEM Passat TDI automatic trans has 6 poles somehow... but then all those other 01E-swapped Passats would have had the same issue I'm having. So why is the ECU taking the signal that the instrument cluster is sending to it, and inflating the result by 15%?
For the record, the ECU is coded for a manual transmission and the tune has all the right gear and final drive ratios entered. And since it was for a B5.5 Passat, tire size is identical between the two cars. I'm not the first person to mate this engine to an 01E, although I may be the first to do it on a B5.5 A4 quattro.
